The present invention refers to a placeholder for implantation into a human or animal body, especially as a placeholder for vertebrae or vertebral discs, a method for manufacturing such a placeholder, and a modular system for such a placeholder.
Placeholders, especially for vertebrae or vertebral discs are known. For example, DE 19504867 C1 discloses a placeholder in the shape of a cylindrical-tubular body with a plurality of rhombic or diamond-shaped openings that are arranged in rows and columns. At the ends of the cylindrical tube are provided projecting serrations and recesses in correspondence with the rhombi that serve for engaging with adjacent vertebrae or adjacent tissue. The diamond-shaped openings facilitate in-growth of the tissue into the implant, such that the latter may knit well with the body.
Moreover, an implant is known from US 2005/0015154 which has a scaffold-like structure in which the latticework extends over the full body or through the entire body of the implant. Such integral latticework structures are intended for use especially in replacement implants for joints, such as hips, knee joints, shoulder joints and the like. However, such integral latticework structures are difficult to manufacture and have to be adjusted and manufactured individually to suit every application case.
DE 101 38 079 AI discloses a placeholder of adjustable axial length in which two sleeve-like parts are arranged adjustably inside one another, more precisely via a lever arrangement over which the parts are connected. Although this device facilitates very precise length adjustment, the lever arrangement is complicated to manufacture.
DE 198 04 765 C2 discloses a placeholder for insertion between two vertebrae with an adjustable axial length. The total length is adjusted by moving an external tube relative to an internal tube. The length adjustment proceeds stepwise by means of catches.
DE 697 19 431 T2 describes a longitudinally adjustable vertebral disc placeholder in which two sleeve bodies arranged telescopically inside one another are adjusted relative to each other and are lockable via screw arrangements. However, this arrangement does not uniformly distribute the load across the screw connections and does not effectively allow in-growth by the surrounding tissue because of the close arrangement of the sleeve bodies.
US 2003/0078660 discloses an implant that may be used as a placeholder in which the implant has a sleeve-like body that is corrugated. This corrugated body may in turn be arranged inside a further sleeve body. However, the corrugated form of the one implant part again makes for complicated manufacture.
EP 09 047 51 AI describes a tubular support body for vertebrae having two cages guided in one another which may be connected to each other by a projecting stud on the jacket surface of the one cage and axial feed channels in the jacket of the other cage. With this arrangement, facilitating of latching positions at different depths is provided. However, the support body is limited in variability by the feed channels.
Based on the above, there is a need for an implant which is easy to manufacture and versatile in use, can provide load dissipation, allows in-growth into human or animal tissue, and is suitable for use as placeholder in the spine, that is, for vertebral discs and vertebrae, but also for tubular bones of the upper and lower extremities.